#include<iostream>
using namespace std;
int exam5_18()
{
	char s[1000];
	int i = 0, n = 0;
	while ((s[n] = getchar()) != '\n')
		n++;
	n--;
	while (s[i] == s[n - i])
		i++;
	if (i > n / 2)
		cout << "yes";
	else cout << "no";
	return 0;

}